In one type of injection blow molding machine for forming plastic hollow articles such as containers, known as the Jomar type or Rainville type, a turret supporting a plurality of sets of core rods is rotated about a vertical axis bringing each set of core rods successively into a first position for injection molding plastic parisons, a second position for blow molding a plurality of parisons and a third position where the blown hollow plastic articles are discharged. In such blow molding machines, a set of injection molding molds are provided at the first station and a set of blow molding molds are provided at the second station. The molds are opened simultaneously and closed simultaneously about the cores.
Among the objectives of the present invention are to provide an injection blow molding machine for forming plastic hollow articles such as containers which has an upper set and a lower set of molds which are associated with a turret supporting upper and lower sets of core rods, whereby a greater number of hollow containers or articles may be made; which machine can utilize existing molds; which does not substantially require an extended time cycle; and which utilizes the existing plant floor space as that for the conventional type machines.
In accordance with the invention, a method and apparatus is provided for forming plastic hollow articles such as containers which includes a turret that includes an upper head and a lower head, each of which supports circumferentially spaced sets of core rods. The heads are rotated about a vertical axis and also are moved upwardly and downwardly about the vertical axis for positioning the core rods within the cavities of upper injection mold and upper blow mold and a lower set of injection and a lower set of blow molds. Each mold has an upper half and a lower half. The lower half of the upper mold is mounted in fixed position and the upper half of the lower mold is mounted in fixed position. The upper half of the upper mold and the lower half of the lower mold are movable axially vertically toward and away from their respective fixed mold halves to close about parisons on the core rods. The upper and lower injection molds are supplied with molten plastic through a manifold to which molten plastic material is supplied from an extruder nozzle tip of an extruder.